The invention relates to night vision scopes, particularly, to a night vision scope with improved voltage supply.
Night vision scopes are used generally by military and law enforcement personnel for operations in low light conditions. This enables military and law enforcement personnel to use the night vision scopes to observe conditions at night and in dark buildings. A night vision scope allows the user to continue to make tactical advances and observe hostile tactical advances. New night vision scopes are also designed to assist pilots of helicopters and planes to more easily fly at night.
Early night vision scopes allowed the user to observe light in the infrared spectrum. To do so, sufficient infrared light, invisible to the human eye, had to be supplied by beacons to illuminate an area. These scopes were used for only a limited period of time because of the concern that hostile forces could use similar night vision scopes to locate the infrared beacon and its user.
Currently, night vision scopes utilize image intensification technologies. That is, the night vision scope receives ambient light from the environment and intensifies the image to produce an output image which is visible to the human eye. The present generation of night vision scopes operate to intensify low levels of visible light and make visible the light from the infrared spectrum.
The image intensification process involves conversion of the received ambient light into electron patterns, intensification and energization of the electron patterns, and conversion of the electron patterns into light visible to the observer.
Use by law enforcement officials and army personnel during active engagement with hostile forces requires that the night vision scopes be rugged and light weight. Further, it is important that the voltage supply for the night vision scope be dependable, light weight, and easily renewed. In constructing a rugged night vision scope it is important for the scope to be impervious to shocks and environmental conditions, such as moisture. Accordingly, the voltage supply must also be impervious to environmental conditions.
Night vision scopes require batteries to supply the power. Either a single specialized battery or two conventional batteries can be used. Typical night vision scopes use two batteries. Use of two batteries instead of one increases the weight of the night vision scope which is a significant disadvantage.
Since night vision scopes are designed to be light weight, using one battery is preferable to using two batteries. However, due to battery design constraints single batteries of suitable size which provide the correct voltage for night vision scopes are not generally manufactured. Thus, specialized batteries must be custom designed and manufactured at great expense.
Any battery used in a night vision scope must be easily replaceable but sealed against water leakage into the battery area. When using two batteries, such as 1.5 volt DC batteries, the container for these batteries must be oval shaped to accept both batteries. The oval shape of the battery container makes it difficult to seal the container to make it water tight because specialized seals are required.
If only one battery is used, a single cylindrical battery container can be used in combination with an O-ring of conventional construction to accomplish the seal desired. However, as discussed above, single batteries must be custom made to provide the correct voltage for a night vision scope.
A voltage step-up circuit could be used as part of the voltage supply in conjunction with a voltage source, such as a battery, to increase the voltage supplied to a value above the voltage of the battery alone. However, voltage step-up circuits often require complex active elements which increase the chance of a malfunction of the circuit. Further, additional components for a voltage step-up circuit can increase the weight of the night vision scope.
Voltage step-up circuits are known. For example, a voltage step-up circuit may be constructed utilizing a Maxim Low Voltage Step-Up DC-DC convertor manufactured by Maxim Integrated Products. This circuit utilizes the charging and discharging of an inductor to step-up a battery voltage.
In addition to stepping up the voltage from a battery, it is sometimes desirable to provide for a battery having a voltage greater than the necessary output voltage from the voltage supply circuit. For instance, in very cold weather an alkaline battery does not function properly. If a lithium battery is used which has a voltage output greater than the desired voltage, the voltage supply circuit must also limit the voltage output to protect the night vision scope elements.
However, such a step-up circuit has not been used in the field of night vision scopes. There are numerous reasons for this nonuse, such as the desire for compact size, for ruggedness, and for light weight.